As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: PACKS HAS AN OIL SMELL. BELIEVED TO BE COMING FROM PACK 1. MAINTENANCE FOUND COKING ON THE GEARBOX VENT TUBE UNION. MAINTENANCE REPLACED GEARBOX VENT TUBE AND UNION, AND REPLACED ALL ASSOCIATED SEALS ON THE APU AIR/OIL SEPERATOR IAW JOB CARD 26L00021002.